Carboplatin-induced upregulation of pan ß-tubulin and class III ß-tubulin is implicated in acquired resistance and cross-resistance of ovarian cancer.

Resistance to platinum- and taxane-based chemotherapy represents a major obstacle to long-term survival in ovarian cancer (OC) patients. Here, we studied the interplay between acquired carboplatin (CBP) resistance using two OC cell models, MES-OV CBP and SK-OV-3 CBP, and non-P-glycoprotein-mediated cross-resistance to paclitaxel (TAX) observed only in MES-OV CBP cells. Decreased platination, mesenchymal-like phenotype, and increased expression of α- and γ-tubulin were observed in both drug-resistant variants compared with parental cells. Both variants revealed increased protein expression of class III ß-tubulin (TUBB3) but differences in TUBB3 branching and nuclear morphology. Transient silencing of TUBB3 sensitized MES-OV CBP cells to TAX, and surprisingly also to CBP. This phenomenon was not observed in the SK-OV-3 CBP variant, probably due to the compensation by other ß-tubulin isotypes. Reduced TUBB3 levels in MES-OV CBP cells affected DNA repair protein trafficking and increased whole-cell platination level. Furthermore, TUBB3 depletion augmented therapeutic efficiency in additional OC cells, showing vice versa drug-resistant pattern, lacking ß-tubulin isotype compensation visible at the level of total ß-tubulin (TUBB) in vitro and ex vivo. In summary, the level of TUBB in OC should be considered together with TUBB3 in therapy response prediction.

Distinctive Nucleic Acid Recognition by Lysine-Embedded Phenanthridine Peptides.

Three new phenanthridine peptide derivatives (19, 22, and 23) were synthesized to explore their potential as spectrophotometric probes for DNA and RNA. UV/Vis and circular dichroism (CD) spectra, mass spectroscopy, and computational analysis confirmed the presence of intramolecular interactions in all three compounds. Computational analysis revealed that compounds alternate between bent and open conformations, highlighting the latter's crucial influence on successful polynucleotide recognition. Substituting one glycine with lysine in two regioisomers (22, 23) resulted in stronger binding interactions with DNA and RNA than for a compound containing two glycines (19), thus emphasizing the importance of lysine. The regioisomer with lysine closer to the phenanthridine ring (23) exhibited a dual and selective fluorimetric response with non-alternating AT and ATT polynucleotides and induction of triplex formation from the AT duplex. The best binding constant (K) with a value of 2.5 × 107 M-1 was obtained for the interaction with AT and ATT polynucleotides. Furthermore, apart from distinguishing between different types of ds-DNA and ds-RNA, the same compound could recognize GC-rich DNA through distinct induced CD signals.

Transcriptome analysis of newly established carboplatin-resistant ovarian cancer cell model reveals genes shared by drug resistance and drug-induced EMT.

BACKGROUND: In ovarian cancer (OC) therapy, even initially responsive patients develop drug resistance. METHODS: Here, we present an OC cell model composed of variants with differing degrees of acquired resistance to carboplatin (CBP), cross-resistance to paclitaxel, and CBP-induced metastatic properties (migration and invasion). Transcriptome data were analysed by two approaches identifying differentially expressed genes and CBP sensitivity-correlating genes. The impact of selected genes and signalling pathways on drug resistance and metastatic potential, along with their clinical relevance, was examined by in vitro and in silico approaches. RESULTS: TMEM200A and PRKAR1B were recognised as potentially involved in both phenomena, also having high predictive and prognostic values for OC patients. CBP-resistant MES-OV CBP8 cells were more sensitive to PI3K/Akt/mTOR pathway inhibitors Rapamycin, Wortmannin, SB216763, and transcription inhibitor Triptolide compared with parental MES-OV cells. When combined with CBP, Rapamycin decreased the sensitivity of parental cells while Triptolide sensitised drug-resistant cells to CBP. Four PI3K/Akt/mTOR inhibitors reduced migration in both cell lines. CONCLUSIONS: A newly established research model and two distinct transcriptome analysis approaches identified novel candidate genes enrolled in CBP resistance development and/or CBP-induced EMT and implied that one-gene targeting could be a better approach than signalling pathway inhibition for influencing both phenomena.

Styryl dyes with N-Methylpiperazine and N-Phenylpiperazine Functionality: AT-DNA and G-quadruplex binding ligands and theranostic agents.

New monomethine, unsymmetrical styryl dyes consisting of benzothiazole and N-methylpiperazine or N-phenylpiperazine scaffolds were synthesized, and their binding affinities for different ds-polynucleotides and G-quadruplex were studied. Substitution of piperazine unit with methyl or phenyl group strongly influenced their binding modes, binding affinities, spectroscopic responses and antiproliferative activities. Compounds with N-methylpiperazine substituents showed a significant preference for AT-DNA polynucleotides and demonstrated AT-minor groove binding, which manifested in strong fluorescence increase, significant double helix stabilization, and positive induced circular dichroism spectra. These compounds formed complexes with G-quadruplex by π-π stacking interactions of dye with the top or bottom G-tetrad. Bulkier compounds with N-phenylpiperazine function are probably bound to ds-polynucleotide by partial intercalation between base pairs. On the other hand, they showed stronger stabilization of G-quadruplex compared to methyl-substituted compounds. Fluorimetric titrations pointed to possible mixed stoichiometry's: 1:1 complex with π-π stacking interactions of dye on the top or bottom G-tetrad and 1:2 complex with dye positioned between two G-quadruplex molecules. Bulkier dyes with N-phenylpiperazine fragments demonstrated micromolar and submicromolar antiproliferative activity that was especially pronounced for leukaemia and lymphoma. Flow cytometric assay shows dose- and time-dependent increase in SubG0/G1 phase. Furthermore, the compounds enter the cells readily and accumulate in the mitochondrial space, co-localize with the standard mitochondrial markers.

Cancer drug resistance induced by EMT: novel therapeutic strategies.

Over the last decade, important clinical benefits have been achieved in cancer patients by using drug-targeting strategies. Nevertheless, drug resistance is still a major problem in most cancer therapies. Epithelial-mesenchymal plasticity (EMP) and tumour microenvironment have been described as limiting factors for effective treatment in many cancer types. Moreover, epithelial-to-mesenchymal transition (EMT) has also been associated with therapy resistance in many different preclinical models, although limited evidence has been obtained from clinical studies and clinical samples. In this review, we particularly deepen into the mechanisms of which intermediate epithelial/mesenchymal (E/M) states and its interconnection to microenvironment influence therapy resistance. We also describe how the use of bioinformatics and pharmacogenomics will help to figure out the biological impact of the EMT on drug resistance and to develop novel pharmacological approaches in the future.

Tumor microenvironment and epithelial mesenchymal transition as targets to overcome tumor multidrug resistance.

It is well established that multifactorial drug resistance hinders successful cancer treatment. Tumor cell interactions with the tumor microenvironment (TME) are crucial in epithelial-mesenchymal transition (EMT) and multidrug resistance (MDR). TME-induced factors secreted by cancer cells and cancer-associated fibroblasts (CAFs) create an inflammatory microenvironment by recruiting immune cells. CD11b+/Gr-1+ myeloid-derived suppressor cells (MDSCs) and inflammatory tumor associated macrophages (TAMs) are main immune cell types which further enhance chronic inflammation. Chronic inflammation nurtures tumor-initiating/cancer stem-like cells (CSCs), induces both EMT and MDR leading to tumor relapses. Pro-thrombotic microenvironment created by inflammatory cytokines and chemokines from TAMs, MDSCs and CAFs is also involved in EMT and MDR. MDSCs are the most common mediators of immunosuppression and are also involved in resistance to targeted therapies, e.g. BRAF inhibitors and oncolytic viruses-based therapies. Expansion of both cancer and stroma cells causes hypoxia by hypoxia-inducible transcription factors (e.g. HIF-1α) resulting in drug resistance. TME factors induce the expression of transcriptional EMT factors, MDR and metabolic adaptation of cancer cells. Promoters of several ATP-binding cassette (ABC) transporter genes contain binding sites for canonical EMT transcription factors, e.g. ZEB, TWIST and SNAIL. Changes in glycolysis, oxidative phosphorylation and autophagy during EMT also promote MDR. Conclusively, EMT signaling simultaneously increases MDR. Owing to the multifactorial nature of MDR, targeting one mechanism seems to be non-sufficient to overcome resistance. Targeting inflammatory processes by immune modulatory compounds such as mTOR inhibitors, demethylating agents, low-dosed histone deacetylase inhibitors may decrease MDR. Targeting EMT and metabolic adaptation by small molecular inhibitors might also reverse MDR. In this review, we summarize evidence for TME components as causative factors of EMT and anticancer drug resistance.

The multi-factorial nature of clinical multidrug resistance in cancer.

Curative cancer therapy remains a major challenge particularly in cancers displaying multidrug resistance (MDR). The MDR phenotype is characterized by cross-resistance to a wide array of anticancer drugs harboring distinct structures and mechanisms of action. The multiple factors involved in mediating MDR may include host factors, tumor factors as well as tumor-host interactions. Among the host factors are genetic variants and drug-drug interactions. The plethora of tumor factors involves decreased drug uptake primarily via impaired influx transporters, increased drug efflux predominantly due to the overexpression of MDR efflux transporters of the ATP-binding cassette superfamily or due to drug efflux mediated by extracellular vesicles (EVs) or drug-loaded lysosomes undergoing exocytosis, deregulation of cell death mechanisms (i.e. anti-apoptotic modalities), enhanced DNA damage repair, epigenetic alterations and/or deregulation of microRNAs. The intratumor heterogeneity and dynamics, along with cancer stem cell plasticity, are important tumor factors. Among the tumor-host interactions are the role of the tumor microenvironment, selective pressure of various stressor conditions and agents, acidic pH and the intracellular transfer of traits mediated by EVs. The involvement of these diverse factors in MDR, highlights the need for precision medicine and real-time personalized treatments of individual cancer patients. In this review, written by a group of researchers from COST Action STRATAGEM "New diagnostic and therapeutic tools against multidrug resistant tumors", we aim to bring together these multidisciplinary and interdisciplinary features of MDR cancers. Importantly, it is becoming increasingly clear that deciphering the molecular mechanisms underlying anticancer drug resistance, will pave the way towards the development of novel precision medicine treatment modalities that are able to surmount distinct and well-defined mechanisms of anticancer drug resistance.

Organometallic ruthenium(II)-arene complexes with triphenylphosphine amino acid bioconjugates: Synthesis, characterization and biological properties.

(p-Cymene)-ruthenium bioconjugates ML (1) and ML2 (2), bearing phosphane ligands substituted with chiral or non-chiral amino acid esters, L, were synthetized and characterized by instrumental methods (NMR, CD, MS) and DFT calculations (using the wB97xD functional). Cytotoxic activity of complexes 1 and 2 was investigated by using human cervical carcinoma cell line (HeLa) and MTT assay. Four (2pG, 2pA, 2mG and 2mA) out of ten synthesized ruthenium complexes showed significant toxicity, with IC50 values of 5-30 µM. Evaluation of the potential biomolecular targets of bioconjugates 2 by UV-Vis, fluorescence and CD spectroscopy revealed no measurable interaction with DNA, but micromolar affinity for proteins. The cytotoxicity of bioconjugates 2 is in correlation with their BSA binding constants, i. e. bioconjugates with lower IC50 values show higher binding affinities towards BSA. Compound 2mG with value of IC50 16 µM was selected for further biological characterization. The higher level of toxicity towards tumor compared to normal cell lines indicates its selective activity, important characteristic for potential medical use. It was detected 2mG caused increase of cells in the S phase of cell cycle and consequential decrease of cells in G0/G1 phase. Additionally, 2mG caused dose- and time-dependent increase of SubG0/G1 cell population, suggesting its ability to induce programmed cell death. Further investigation determined autophagy as the mode of cell death. The role of GSH in HeLa cells response to investigated organometallic ruthenium complexes was confirmed using specific regulators of GSH synthesis, buthionine sulfoximine and N-acetyl-cysteine. Pre-treatment of cells with ethacrynic acid and probenecid emphasized the role of GSH in detoxification of 2mG compound. The amount of total ruthenium accumulation in the cell did not correlate with toxicity of 2pG, 2pA, 2mG and 2mA, suggesting structure dependent differences in either cell uptake or kinetics of ruthenium complexes detoxification. We speculate that ruthenium complexes bind protein-based biomolecules further triggering cell death. Based on the gained knowledge, the synthesis and development of more tumor-specific ruthenium-based complexes as potential anticancer drugs can be expected.

Functional mismatch repair and inactive p53 drive sensitization of colorectal cancer cells to irinotecan via the IAP antagonist BV6.

A common strategy to overcome acquired chemotherapy resistance is the combination of a specific anticancer drug (e.g., topoisomerase I inhibitor irinotecan) together with a putative sensitizer. The purpose of this study was to analyze the cytostatic/cytotoxic response of colorectal carcinoma (CRC) cells to irinotecan, depending on the mismatch repair (MMR) and p53 status and to examine the impact of BV6, a bivalent antagonist of inhibitors of apoptosis c-IAP1/c-IAP2, alone or combined with irinotecan. Therefore, several MSH2- or MSH6-deficient cell lines were complemented for MMR deficiency, or MSH6 was knocked out/down in MMR-proficient cells. Upon irinotecan, MMR-deficient/p53-mutated lines repaired DNA double-strand breaks by homologous recombination less efficiently than MMR-proficient/p53-mutated lines and underwent elevated caspase-9-dependent apoptosis. Opposite, BV6-mediated sensitization was achieved only in MMR-proficient/p53-mutated cells. In those cells, c-IAP1 and c-IAP2 were effectively degraded by BV6, caspase-8 was fully activated, and both canonical and non-canonical NF-κB signaling were triggered. The results were confirmed ex vivo in tumor organoids from CRC patients. Therefore, the particular MMR+/p53mt signature, often found in non-metastasizing (stage II) CRC might be used as a prognostic factor for an adjuvant therapy using low-dose irinotecan combined with a bivalent IAP antagonist.

Integrin αvß3 expression in tongue squamous carcinoma cells Cal27 confers anticancer drug resistance through loss of pSrc(Y418).

Integrins play key roles in the regulation of tumor cell adhesion, migration, invasion and sensitivity to anticancer drugs. In the present study we investigate the mechanism of resistance of tongue squamous carcinoma cells Cal27 with de novo integrin αvß3 expression to anticancer drugs. Cal27-derived cell clones, obtained by transfection of plasmid containing integrin subunit ß3 cDNA, as compared to control cells demonstrate: expression of integrin αvß3; increased expression of integrin αvß5; increased adhesion to fibronectin and vitronectin; resistance to cisplatin, mitomycin C, doxorubicin and 5-fluorouracil; increased migration and invasion, increased amount of integrin-linked kinase (ILK) and decreased amounts of non-receptor tyrosine kinase (Src) and pSrc(Y418). Knockdown of ILK and integrin ß5 in cells expressing integrin αvß3 ruled out their involvement in drug resistance. Opposite, Src knockdown in Cal27 cells which led to a reduction in pSrc(Y418), as well as treatment with the pSrc(Y418) inhibitors dasatinib and PP2, conferred resistance to all four anticancer drugs, indicating that the loss of pSrc(Y418) is responsible for the observed effect. We identified differential integrin signaling between Cal27 and integrin αvß3-expressing cells. In Cal27 cells integrin αv heterodimers signal through pSrc(Y418) while this is not the case in integrin αvß3-expressing cells. Finally, we show that dasatinib counteracts the effect of cisplatin in two additional head and neck squamous cell carcinoma (HNSCC) cell lines Cal33 and Detroit562. Our results suggest that pSrc(Y418) inhibitors, potential drugs for cancer therapy, may reduce therapeutic efficacy if combined with chemotherapeutics, and might not be recommended for HNSCC treatment.

The relationship between platinum drug resistance and epithelial-mesenchymal transition.

One of the most commonly used chemotherapeutics, platinum drugs are used to treat a wide range of cancer types. Although many cancers initially respond well to those drugs, drug resistance occurs frequently and different molecular mechanisms have been associated with it. However, predictive biomarkers of cellular response in specific tumour types still do not exist. Epithelial-mesenchymal transition (EMT) is a malignant cancer phenotype characterized by aggressive invasion and metastasis, and resistance to apoptosis. Recent studies indicate that EMT accompanies the development of drug resistance to a number of cancer chemotherapies. The link between these two phenomena is still not elucidated, although several important molecules involved in both these complex processes, such as transcription factors (SNAIL, TWIST, ZEB, etc.) and miRNAs (miRNA-200 family, miR-15, miR-186, etc.) have been recognized as important. This article reviews numerous unresolved issues regarding platinum drugs resistance and EMT, the complexity of the signalling networks that regulate those two phenomena and their importance in tumour response and spreading which are becoming focuses of interest of many scientists. This article also presents molecules involved in platinum resistance and EMT as possible targets for new cancer therapy.

Discovery of 'click' 1,2,3-triazolium salts as potential anticancer drugs.

BACKGROUND: In order to increase the effectiveness of cancer treatment, new compounds with potential anticancer activities are synthesized and screened. Here we present the screening of a new class of compounds, 1-(2-picolyl)-, 4-(2-picolyl)-, 1-(2-pyridyl)-, and 4-(2-pyridyl)-3-methyl-1,2,3-triazolium salts and 'parent' 1,2,3-triazole precursors. METHODS: Cytotoxic activity of new compounds was determined by spectrophotometric MTT assay on several tumour and one normal cell line. Effect of the selected compound to bind double stranded DNA (ds DNA) was examined by testing its influence on thermal stability of calf thymus DNA while its influence on cell cycle was determined by flow cytometric analysis. Generation of reactive oxygen species (ROS) was determined by addition of specific substrate 5-(and-6)-chloromethyl-2',7'-dichlorodihydrofluorescein diacetate, acetyl ester (CM-H2DCFDA). RESULTS: Parent triazoles were largely inactive, while some of the triazolium salts were highly cytotoxic for HeLa cells. Triazolium salts exhibited high cell-type dependent cytotoxicity against different tumour cells. Selected compound (4-(4-methoxyphenyl)-3-methyl-1-(2-picolyl)-1H-1,2,3-triazolium hexafluorophosphate(V) (2b) was significantly more cytotoxic against tumour cells than to normal cells, with very high therapeutic index 7.69 for large cell lung carcinoma H460 cells. Additionally, this compound was similarly cytotoxic against parent laryngeal carcinoma HEp-2 cells and their drug resistant 7T subline, suggesting the potential of this compound in treatment of drug resistant cancers. Compound 2b arrested cells in the G1 phase of the cell cycle. It did not bind ds DNA, but induced ROS in treated cells, which further triggered cell death. CONCLUSIONS: Our results suggest that the 'click' triazolium salts are worthy of further investigation as anti-cancer agents.

PCB 77 action in ovary cells--toxic effects, apoptosis induction and cell cycle analysis.

CONTEXT: PCB 77 (3,3',4,4'-tetrachlorobiphenyl), a non-ortho congener with planar configuration, has been identified as potential endocrine disrupter capable to increase the risk of reproductive and developmental failure. OBJECTIVE: In the present study, in vitro PCB 77 toxic potential, apoptosis induction and cell cycle alterations were investigated to reveal direct toxic effects on ovarian cells. METHODS: Chinese Hamster Ovary (CHO-K1) cell line was selected as a model system and decreased cell viability was confirmed by application of four bioassays. Cellular morphology and quantitative analysis of apoptotic, necrotic and viable cells were determined with fluorescent microscopy and cell cycle phase distributions by measuring DNA content using flow cytometry. RESULTS: We have indicated Trypan blue exclusion assay as the most sensitive for quantifying cytotoxicity of PCB 77 in terms of IC50 values, while the results obtained by other methods pointed to a possible localized effect on the lysosomes/endosomes (Neutral red), compromised intracellular metabolic processes (MTT) and possible interferation with the rate of protein synthesis (Kenacid blue). The loss of cell viability, as a consequence of treatment with 10-100 µM PCB 77, fundamentally was due to induction of apoptosis with observed common series of specific morphological changes characteristic to apoptotic phenomenon. The level of alterations of normal cell cycle progression was low without significant changes at analyzed time intervals. CONCLUSION: These results indicate toxic outcomes of PCB 77 at ovarian cellular level with regard to potential direct adverse effects to female reproductive system.

3-Acetyl-bis(2-chloro-4-nitrophenyl)triazene is a potent antitumor agent that induces oxidative stress and independently activates the stress-activated protein kinase/c-Jun NH2-terminal kinase pathway.

Previously, we described the synthesis and biological activity of a new class of anticancer molecules that preferentially target malignant cells and may serve as potential antitumor agents. Among several synthesized agents, we selected 3-acetyl-1,3-bis(2-chloro-4-nitrophenyl)-1-triazene (8b) as a representative of the group of 4-nitro-substituted 1,3-diaryltriazenes. The aim of this study was to further investigate the mechanism of cell response to the 8b compound. The HeLa human cervical carcinoma cell line was used as an experimental model to further investigate the mechanism of cell response to the 8b compound. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) colorimetric assay was used to address cell survival, and western blot (immunoblotting) was used for the expression of relevant proteins after 8b drug exposure. The pretreatment of HeLa cells with salubrinal, a specific inhibitor of endoplasmic reticulum (ER) stress, confirmed the importance of ER stress in apoptosis induced by 8b. We also demonstrate that 8b triggers the activation of stress-activated protein kinase/c-Jun NH2-terminal kinase (SAPK/JNK) in a time-dependent and dose-dependent manner. Moreover, the inhibition of SAPK/JNK activity by JNK II before 8b treatment increased the survival rate of HeLa cells relative to survival in the presence of 8b alone, indicating the importance of this kinase in cell death. The simultaneous inhibition of ER stress induction and SAPK/JNK activation increased the survival of HeLa cells upon 8b treatment more than inhibition of both pathways independently, suggesting the separate triggering of both signaling pathways. Our data indicate that cytotoxic activity of the novel compound 8b is based on its ability to induce ER stress and SAPK/JNK signaling pathways independently, driving cells to cell death.

The high-grade serous ovarian cancer metastasis and chemoresistance in 3D models.

High-grade serous ovarian cancer (HGSOC) is the most frequent and aggressive type of epithelial ovarian cancer, with high recurrence rate and chemoresistance being the main issues in its clinical management. HGSOC is specifically challenging due to the metastatic dissemination via spheroids in the ascitic fluid. The HGSOC spheroids represent the invasive and chemoresistant cellular fraction, which is impossible to investigate in conventional two-dimensional (2D) monolayer cell cultures lacking critical cell-to-cell and cell-extracellular matrix interactions. Three-dimensional (3D) HGSOC cultures, where cells aggregate and exhibit relevant interactions, offer a promising in vitro model of peritoneal metastasis and multicellular drug resistance. This review summarizes recent studies of HGSOC in 3D culture conditions and highlights the role of multicellular HGSOC spheroids and ascitic environment in HGSOC metastasis and chemoresistance.

Strong apoptotic response of testis tumor cells following cisplatin treatment.

Most solid metastatic cancers are resistant to chemotherapy. However, metastatic testicular germ cell tumors (TGCT) are cured in over 80% of patients using cisplatin-based combination therapy. Published data suggest that TGCTs are sensitive to cisplatin due to limited DNA repair and presumably also to a propensity to undergo apoptosis. To further investigate this aspect, cisplatin-induced activation of apoptotic pathways was investigated in cisplatin-sensitive testis tumor cells (TTC) and compared to cisplatin-resistant bladder cancer cells. Apoptosis induction was investigated using flow cytometry, caspase activation and PARP-1 cleavage. Immunoblotting and RT-PCR were applied to investigate pro- and anti-apoptotic proteins. Transfections were performed to target p53- and Fas/FasL-mediated apoptotic signaling. Immunoblotting experiments revealed p53 to be induced in TTC, but not bladder cancer cells following cisplatin. Higher levels of pro-apoptotic Bax and Noxa were observed in TTC, anti-apoptotic Bcl-2 was solely expressed in bladder cancer cells. Cisplatin led to translocation of Bax to the mitochondrial membrane in TTC, resulting in cytochrome C release. Cisplatin increased the expression of FasR mRNA and FasL protein in all tumor cell lines. Targeting the apoptotic pathway via siRNA-mediated knockdown of p53 and FAS reduced death receptor-mediated apoptosis and increased cisplatin resistance in TTC, indicating the involvement of FAS-mediated apoptosis in the cisplatin TTC response. In conclusion, both the death receptor and the mitochondrial apoptotic pathway become strongly activated in TTC following cisplatin treatment, explaining, together with attenuated DNA repair, their unique sensitivity toward platinum-based anticancer drugs.

Dissimilar effect of organometallic ruthenium complexes on the viability of MDR and non-MDR experimental models.

Ruthenium complexes containing triphenylphosphine diamide ligands were prepared, characterized, and tested for their biological activity against various cancer cell lines and the malaria parasite, Plasmodium falciparum. The effect of M (mono-substituted) and B (bis-substituted) complexes on the human cervical carcinoma (HeLa) cell line was investigated using the MTT assay. Five (B2, B3, B5, B6, and B13) of the 24 synthesized ruthenium complexes showed significant effects with IC50 values ranging between 0.3 and 2.3 µM. Evaluation of the potential biomolecular targets of B2 and B13 by fluorescence spectroscopy revealed relevant interactions with BSA and only a weak affinity for ctDNA. Complexes M2, B2, M13 and B13 were selected for further biological characterization. Their effect on the viability of two ovarian cancer cell lines was compared to normal cell lines, denoting their selectivity. Upon treatment of four different drug-resistant gynaecological cancer cell lines, differing in their multidrug-resistant phenotypes, the efficacy of the bis-substituted complexes was shown to be greater than their mono-substituted counterparts. The non-MDR cells are sensitive to all the tested complexes, compared to MDR cells which are less sensitive. Upon investigation of complexes M2, M13, B2, and B13 against sensitive and multidrug-resistant parasite strains of P. falciparum, the bis-substituted complexes were again shown to be the most potent, with submicromolar activity against both strains. Furthermore, the resistance indexes for the complexes were approximately equal to 1, which is at least 5-fold lower than chloroquine diphosphate, suggesting the ability of these complexes to retain their activity in resistant forms of the parasite.

Paraptotic Cell Death as an Unprecedented Mode of Action Observed for New Bipyridine-Silver(I) Compounds Bearing Phosphane Coligands.

In this work, we investigated the anticancer activity of several novel silver(I) 2,2'-bipyridine complexes containing either triphenylphosphane (PPh3) or 1,2-bis(diphenylphosphino)ethane (dppe) ligands. All compounds were characterized by diverse analytical methods including ESI-MS spectrometry; NMR, UV-vis, and FTIR spectroscopies; and elemental analysis. Moreover, several compounds were also studied by X-ray single-crystal diffraction. Subsequently, the compounds were investigated for their anticancer activity against drug-resistant and -sensitive cancer cells. Noteworthily, neither carboplatin and oxaliplatin resistance nor p53 deletion impacted on their anticancer efficacy. MES-OV cells displayed exceptional hypersensitivity to the dppe-containing drugs. This effect was not based on thioredoxin reductase inhibition, enhanced drug uptake, or apoptosis induction. In contrast, dppe silver drugs induced paraptosis, a novel recently described form of programmed cell death. Together with the good tumor specificity of this compound's class, this work suggests that dppe-containing silver complexes could be interesting drug candidates for the treatment of resistant ovarian cancer.

Design and evaluation of biological activity of diazenecarboxamide-extended cisplatin and carboplatin analogues.

Construction of a library of structurally diverse diazenecarboxamide-extended cis-[Pt(2-picolyl-1,2,3-triazole)Cl2,] and cis-[Pt(propan-1,3-diamine)CBDCA] (CBDCA = 1,1 -cyclobutanedicarboxylate) complexes 1-4 is described. These compounds retain oxidative properties of parent diazenecarboxamides against glutathione as demonstrated by NMR spectroscopy and high resolution mass spectrometry experiments. Cytotoxic activity of 1-4 was investigated against human cervical carcinoma HeLa cells. Four library members were found to possess moderate cytotoxic activity. Some model compounds were also examined, returning [PtCl2L2] (L = 1-(2-picolyl)-4-phenyl-1H-1,2,3-triazole) as the most potent under this investigation with IC50 of 19.05 microM, comparable to that of cisplatin (IC50 = 16.3 microM).